Part 6

7(6'). Forearm less than 80; large, sharp claw on second phalanx of second digit; four upper incisors =Rousettus=, p. 787

7'. Forearm more than 90; small, blunt claw on second phalanx of second digit; two upper incisors =Dobsonia=, p. 807

Family PTEROPODIDAE

Subfamily Pteropodinae

Rousettus Gray

1821. Rousettus Gray, London Medical Repository, 15:299, April 1.

1843. Xantharpyia Gray, List of species ... British Museum, p. 37.

1852. Cynonycteris Peters, Reise nach Mossambique, p. 25.

The genus Rousettus occurs throughout the tropical regions of the Old World, and in the Solomons is readily distinguished from all other megachiropteran genera by having both a small claw on the second digit and free caudal vertebrae. The oriental species have been divided into two groups on the basis of size (Tate, 1942:344). The subspecies Rousettus amplexicaudatus hedigeri appears to be the sole representative of this genus in the Solomon Islands. Prior to 1953, several workers (Thomas, 1887b:323, 1888b:475; Matschie, 1899:68; Sanborn, 1931:11) used the name Rousettus amplexicaudatus brachyotis for it, but Pohle (1953) suggested that the specimens from the Solomons recorded by earlier workers were R. a. hedigeri named by him on the basis of the specimen that he saw from Bougainville.

=Rousettus amplexicaudatus=

Rousettus amplexicaudatus has at least three subspecies, one of which is endemic to the Solomon Islands. The species is wide-ranging, being known from as far west as Thailand (Ellerman and Morrison-Scott, 1966:93) and as far east as the Solomons.

=Rousettus amplexicaudatus hedigeri= Pohle

1953. Rousettus amplexicaudatus hedigeri Pohle, Z. Säugetierk., 17:127, October 27, type from Bougainville.

1887. Cynonycteris brachyotis, Thomas, Proc. Zool. Soc. London, p. 323, March 15; 1888, Thomas, Proc. Zool. Soc. London, p. 475, December 4, from Fauro.

1889. Xantharpyia brachyotis, Matschie, Die Megachiroptera ... naturkunde, p. 68, from Guadalcanal.

1912. Rousettus brachyotis, Andersen, Catalogue of the Chiroptera ... British Museum, 1:809; 1931, Sanborn, Publ. Field Mus. Nat. Hist., Zool. Ser., 18:11, February 12, from Santa Ysabel.

Specimens examined (20 males and 21 females; all in alcohol; ten crania extracted and cleaned).--Guadalcanal in May, 23863, 23915; Fauro in April, 23804-5; Malaita in June, 24079; Choiseul in March, 23563-4, 23616, 23627, 23630, 23632-3, 23642, 23658, 23663-4, 23680, 23692-3, 23713, 23722; Kolombangara in January and February, 23343, 23366, 23382-4, 23389-90, 23408-9, 23424, 23455, 23471-4, 23501.

Measurements.--Average and extreme external measurements of 13 males and 18 females are, respectively, as follows: Length of head and body, 104.4 (99-118), 108.6 (104-117); tail vertebrae, 16.8 (13-19), 17.6 (15-24); hind foot, 18.0 (16-19), 16.2 (12-18); ear, 15.9 (15-17), 15.0 (14-16); length of forearm, 70.1 (66.0-74.1), 68.1 (65.0-69.1). Average and extreme measurements of skulls of five males and five females are, respectively, as follows: Greatest length of skull, 33.2 (33.0-33.7), 31.5 (30.9-32.1); condylobasal length, 31.3 (30.9-31.9), 30.1 (29.3-30.8); palatal length, 14.0 (13.3-14.8), 13.3 (13.0-13.7); zygomatic breadth, 20.8 (19.8-21.8), 19.4 (18.7-20.8); length of maxillary tooth-row, 11.0 (10.9-11.3), 10.3 (10.1-10.6); length of mandibular tooth-row, 12.6 (12.4-12.9), 11.8 (11.7-12.2).

Remarks.--The specimens from Choiseul, Kolombangara, and Malaita islands provide new records of distribution for Rousettus amplexicaudatus hedigeri (Fig. 3). It was described as smaller than R. a. brachyotis Dobson, which is known from New Guinea, Amboina, and the Bismarck Archipelago (Pohle, 1953:127-128). Andersen (1912:809) gave the range of length of forearm in R. a. brachyotis as 73-81, whereas Pohle (1953:127) gave the length of forearm of the type specimen of R. a. hedigeri (adult male) as 67. Measurements of specimens examined by me indicate that hedigeri occurs throughout the Solomon Islands. Cranial measurements of my specimens and Pohle's type are less than those of R. a. brachyotis (see Andersen, 1912:48).

Sanborn (1931:11) noted that the forearms of three males examined by him were longer than that of a female. Mean and range for length of forearm of males and females listed herein, respectively, are 70.1 (66.0-74.1) and 68.1 (65.0-69.1). Also, each of seven cranial measurements taken by me averaged more in males than in females. Sagittal and lambdoidal crests are more prominent in males than in females.

TABLE 1. A Summary of Breeding Data for Females of Rousettus amplexicaudatus hedigeri Collected December to June.

===========+===========+==============+===========+============= | Total | Number | | Number of MONTH | number | adult | Number | immature | collected | collected | lactating | individuals -----------+-----------+--------------+-----------+------------- December | 3 | 3 | 3 | 0 January | 11 | 11 | 8 | 0 February | 6 | 0 | -- | 1 March | 16 | 1 | 0 | 9 April | 2 | 2 | 0 | 0 June | 1 | 1 | 0 | 0 -----------+-----------+--------------+-----------+-------------

As shown in Table 1, adult females obtained in December and January were lactating when captured whereas those obtained in March, April, and June were not. More than half of the individuals collected in March were immature (judging from small size, unfused epiphyses, and lack of wear on teeth). The immature individuals probably had been nursing in December and January.

=Pteralopex= Thomas

1888. Pteralopex Thomas, Ann. Mag. Nat. Hist., ser. 6, 1:155, February 1.

1762. Pteropus Brisson, Regnum animale ..., ed. 2, p. 153.

Pteralopex, with one species and two subspecies, is the only megachiropteran genus endemic to the Solomons. Thomas (1888b:475) considered this unusual bat a relic, isolated from the time when pteropodids had cuspidate cheek-teeth. Although two workers (Matschie, 1899:11; Simpson, 1945:54) have synonymized Pteralopex with Pteropus, I regard Pteralopex as a morphologically distinct genus.

Individuals of Pteralopex can be distinguished from all species of Pteropus in the Solomon Islands by the following features: wing membranes originate along dorsal midline; braincase diminutive relative to rest of skull; sagittal crest pronounced; cheek-teeth cuspidate, broad and massive; i2 about 10 times larger than i1; upper canines with well-developed secondary cusp; postorbital process fused with zygomatic arch, forming complete bony ring around orbit.